This invention relates to spring-loaded, inert railway car retarders, and more particularly to an improved retarder with release means.
The basic function of a fixed, spring-loaded, inert retarder is to offer a preset resistance to all railway cars entering into it. This is done with devices which are installed in a railway track in order to retard or to completely arrest the rolling movement of cars by pressing an auxiliary friction rail against the car wheels so that the latter are braked by friction. U.S. Pat. No. 2,904,133 "Railway Car Retarder" to John A. Bodkin, et al, best describes this type of retarder.
By their natures, inert retarders have a preset resistance which cannot be varied without a time consuming readjustment of the multiple fastenings that hold the retarder in place. Consequently cars caught in the retarder must be pulled through by a locomotive or other external source of comparable motive power causing wear and noise. In many industrial applications, however, the cars are positioned by a fixed car puller or small engine, which lacks the power to move cars through the retarder, thereby limiting its applicability.
Because of an inert retarder's fixed braking force, cars with different weights are slowed to different speeds. This presents a problem when the retarder is used in hump yards where cars must maintain a certain speed to negotiate turns, roll to the end of the track and couple without damage.
Another limitation experienced with conventional inert retarders is with the friction rails themselves. Retarder friction rails must be replaced periodically as they wear out. This is a time consuming operation that usually requires the dismantling of the entire retarder assembly.